1. Field of the Invention
The present invention relates to a belt-type continuously variable transmission incorporated into a vehicle. Particularly, the present invention relates to a cooling structure of the belt-type continuously variable transmission.
2. Description of the Related Art
United States Patent Application Publication No. 2010/0167853 discloses a cooling structure of a conventional V-belt-type continuously variable transmission (CVT) built into a utility vehicle. In the continuously variable transmission disclosed in this literature, a fixed sheave of a drive pulley and a fixed sheave of a driven pulley are provided with fins which function as centrifugal fans, and air introduced from outside into a case is flowed through the drive pulley and then the driven pulley, thereby cooling these pulleys and a V-belt.
An air-intake duct is mounted to the peripheral wall of the case surrounding the drive pulley. Outside air suctioned through the air-intake duct is guided to an air entrance closer to a center of the drive pulley, and is blown toward the outer periphery of the drive pulley as cooling air. Then, the cooling air is guided to an air entrance closer to the center of a driven pulley by an air guide member provided between the drive pulley and the driven pulley, the cooling air is blown toward the outer periphery of the driven pulley, and then the cooling air is discharged through an air discharge duct which opens the peripheral wall of the case.
However, in the above conventional continuously variable transmission, the flow of the cooling air blowing toward the outer periphery of the drive pulley and the flow of the cooling air blowing toward the outer periphery of the driven pulley interfere with each other in a complex manner inside a narrow space of the case. Therefore, it is difficult to form a flow of the cooling air directed from the drive pulley toward the driven pulley as intended.